title: Sugar-binding sites on the surface of the carbohydrate-binding module of CBH I from Trichoderma reesei.
abstract: Molecular dynamics simulations were carried out for a system consisting of the carbohydrate-binding module (CBM) of the cellulase CBH I from Trichoderma reesei (Hypocrea jecorina) in a concentrated solution of β-D-glucopyranose, to determine whether there is any tendency for the sugar molecules to bind to the CBM. In spite of the general tendency of glucose to behave as an osmolyte, a marked tendency for the sugar molecules to bind to the protein was observed. However, the glucose molecules tended to bind only to specific sites on the protein. As expected, the hydrophobic face of the sugar molecules, comprising the axial H1, H3, and H5 aliphatic protons, tended to adhere to the flat faces of the three tyrosine side chains on the planar binding surface of the CBM. However, a significant tendency to bind to a groove-like feature on the upper surface of the CBM was also observed. These results would not be inconsistent with a model of the mechanism for this globular domain in which the cellodextrin chain being removed from the surface of crystalline cellulose passes over the upper surface of the CBM, presumably then available for hydrolysis in the active site tunnel of this processive cellulase.
authors.affiliation: Department of Life Sciences, University of Trieste, Trieste, Italy.
authors.forename: Letizia
authors.initials: L
authors.lastname: Tavagnacco
authors.forename: Philip E
authors.initials: PE
authors.lastname: Mason
authors.forename: Udo
authors.initials: U
authors.lastname: Schnupf
authors.forename: Felicia
authors.initials: F
authors.lastname: Pitici
authors.forename: Linghao
authors.initials: L
authors.lastname: Zhong
authors.forename: Michael E
authors.initials: ME
authors.lastname: Himmel
authors.forename: Michael
authors.initials: M
authors.lastname: Crowley
authors.forename: Attilio
authors.initials: A
authors.lastname: Cesàro
authors.forename: John W
authors.initials: JW
authors.lastname: Brady
mesh_terms: D001665:Binding Sites; D002241:Carbohydrates / Q000737:chemistry*; D002480:Cellulase / Q000737:chemistry* / Q000378:metabolism*; D002482:Cellulose / Q000737:chemistry; D005947:Glucose / Q000737:chemistry; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D014242:Trichoderma / Q000201:enzymology*
chemical_list: D002241:Carbohydrates; D002482:Cellulose; D002480:Cellulase; D005947:Glucose